Four men with metastatic carcinoma (two bronchus, one stomach, one primary unknown) and ectopic placental protein production (one chorionic gonadotropin (hCG and its alpha subunit; one placental lactogen (hPL); one hCG alone; one hCG and hPL) were studied with serial retrospective measurements of the ectopic protein concentrations in serum, correlated with objective assessment of clinical status. The biochemical marker and clinical response were documented during treatment with a variety of agents and during periods without therapy. Of nine assessable periods, seven showed concordance of biochemical marker and clinical responses.